This example shows an interactive scatter plot of the Iris dataset, encoding petal length and sepal width along the x- and y-axes, with species mapped to color. The ordinal color legend uses `d3.scaleOrdinal` with SVG circles; hovering over a legend item highlights only the corresponding species by filtering the data with React state. Non-hovered marks fade via opacity, and the axis components use `d3.scaleLinear` and `extent` to derive domains. The data loads asynchronously through `d3.csv`.